Reduced pressure environment techniques for depositing films of hard inorganic materials up to several micron thickness are sputtering, plasma polymerization, physical vapor deposition, chemical vapor deposition, ion plating, etc. Hard inorganic materials which can be prepared using these techniques include metals, metal oxides, metal nitrides, mixtures, etc. Often the partial pressures of key gases in the deposition environment are controlled to effect chemical reactions between depositing metal species. Thus, a film formed on a substrate by reactive sputtering or reactive deposition can be a compound derived from a metal and a controlling gas, i.e. aluminum oxide produced by sputtering aluminum in oxygen. Sometimes the controlling gases are used to sustain a plasma in the deposition environment. Ion assisted deposition is a technique in which the controlled gas is ionized and is used to bombard the deposition surface to modify the morphology and physical properties of the resulting film. A critical review of vapor deposition technology related to hard coatings was presented by J. E. Sundgren and H. T. C. Hentzell in J. Vac. Sci. Tech. A4(5), September/October 1987, 2259-2279. A more complete review of techniques involved in formation of thin films in reduced pressure environments is the book edited by J. L. Vossen and W. Kern, Thin Film Processes, Academic, New York, 1978.
Thin film literature describes the use of both organic and inorganic materials as release layers for the preparation of free standing films. The impetus for preparing such films has been to allow a free standing material to be analyzed by microscopy, x-ray diffraction or surface analytical techniques.
Recent articles on thin film preparation include Yabinouitch, E., Gmitter, J. P., Haubison, J. P. and Bhat, R., Appl. Phys. Letter, 51(26), Dec. 28, 1987, 2222-2224 on etching Al/As to form free standing GaAlAs films; Clevenger, L. A., Thompson, C. V. and Cammarata, R. C., Appl. Phys. Letter, 52(10), Mar. 7, 1988, 795-797 on using commercial photoresists as supports; Ryszard Lamber, Thin Boehmite Films: Preparation and Structure; Journal of Materials Science Letters, 5(1986), 177-178; and Huling and Messing, J. Am. Ceram. Soc., 71(4), 1988, C222-C224, on coating on camphor and subliming to obtain free standing mullite.
Patents dealing with thin film deposition include U.S. Pat. Nos. 4,604,181 and 4,702,963.
While it would be desirable to deposit thin metal-containing films on polymer compositions to serve as wear layers, direct application often destroys or degrades the polymer composition or results in poor adhesion or film quality. Thus, it would advance the art to provide a suitable means for joining a thin metal-containing film with polymer compositions.